Thanks for your info. However your dicription did not made me satisfied.
1-Grid lines were there to show what the deck flut direction should be & they are horizontal & has nothing to do with roof slope.
2-I tried to use polyline which I created by AutoCAD 3D polyline & did not accept, aparently Graitec dosenot recognize 3D polyline.
3-I requested to send me the model you created but never got any respond.
4-I used AutoCAD 3 dimension USC, create a triangle & used clading icon (blue color) to fill the rectangle, then trim all panels to fit into roof frame.